Upper Parts Kit (UPK) for Glock 17 - Gen 3. These are great for completing your custom slide. All parts are from US manufacturer. All Parts are made to the highest tolerance to the original specification. These parts are Gen 3 specific and not compatible with any other Gens. Features : Upper Parts Kit For GLOCK 17 Gen 3 GLOCK is a registered trademark of GLOCK Inc. 3CR Tactical is not affiliated with, endorsed by, or sponsored by GLOCK Inc. Any reference to GLOCK products is for identification and compatibility purposes only.